Gaseous discharge device



A914125, 1950 A. H. REEVES` I 2,505,006

GASEOUS DISCHARGE DEVICE Filed oet. 3, i947 2 sheets-sheet 1 l 16 2l 22 T E /Z0 l 19 I 1 2 I? l l 5673.910/H2/314F2 25 s/G/vfm PULSE GIE/VE/PHTORZG l l I I-l A i i 7px I M l a/ l 52'/ fi@ I 30 c/ H 29 OUW;

L* l A5/ 0 t MASTER /26 l I PULSE Q .2 G51/RAMP 2 ATTORN EY April 25, 1950 A. H. REEVES GAsEoUs DISCHARGE DEVICE 2 sheets-sheet 2 Filed OC. 3, 1947 wb. I

INVENTO R HLEC HARLEY REEVES ISO.

ATTORNEY Patented Apr. 25, 1950 statt GASEOUS DISCHARGE DEVICE Alec Harley Reeves, London, England, assignor to International Standard Electric Corporation,

New York, N. Y., a corporation of Delaware Application October 3, 1947, Serial No. 777,817

In Great Britain October 3, 1946 9 Claims.

1 This invention relates to electronic devices using multigap cold cathode gaseous discharge tubes.

formation concerning the pulses of a train of electric pulses and deliver up that information, when required, in a number of alternative forms.

According to one of its features, the invention consists of an electronic device which comprises a cold cathode gaseous discharge tube having a number of gaps adapted to fire in a predetermined order on the application to the said gaps of consecutive pulses of electrical energy due to the influence of a fired gap on the potential required to fire an adjacent uniired gap, means for applying in turn to the said tube a first group of pulses and a second group of pulses and means for giving a signal dependent on the firing of a `predetermined gap during the application of the second group of pulses.

The nature of the invention will be more readily appreciated from a description of certain embodiments illustrated in the accompanying drawings, in which:

Fig. 1 is a circuit diagram of a device adapted to record a number of pulses and subsequently `deliver a signal or signals depending on that number;

Fig. 2 is a circuit diagram of a device adapted to record a number of pulses and then continuously deliver information characteristic of that number in the form of a delay or phase position in relation to a recurrent cycle of pulses.

Both these embodiments make use of tubes of the type described in my application, Serial No. 763,655, filed July |25, 1947, now abandoned, and in my joint application with C. H. Hough, Serial AN0. 763,656, filed July 25, 1947, of which a brief description will now be given. y

In these specifications there are described cold cathode gaseous discharge tubes having a number of discharge gaps which re in succession in a predetermined order, on application of pulses to the said gaps in common, due to ionisation of an unred gap, .caused by the discharge in an adjoining fired gap.

A rst pulse applied to the tube will re only a predetermined gap, called the starting gap, and various alternative measures to ensure this include the closer spacing of the electrodes of the starting gapincomparison with the other gaps, a bias potential applied to the starting gap only, or the provision of a permanently discharging gap, called a pilot gap, adjoining the starting gap, vcausing this gap to be permanently ionised. 55

After a sequence of discharges of the gaps of the tube, and when the last gap (in the predetermined order) has red, all discharges are extinguished and the tube is allowed to deionise before the commencement of another firing cycle. If it is required to operate such a tube from a continuous sequence of regularly spaced pulses, as in the case of the embodiment illustrated in Fig. 2, a limit is set to the permissible frequency of pulse repetition by the need for a time interval between pulses, long enough to allow the gaps to become deionised (except the starting gap when a pilot gap is provided as previously described).

If gaps (except as aforesaid) remained ionised, there would be no guarantee that the starting gap would fire rst, in preference to the others, in a second or subsequent cycle of pulses nor that the predetermined firing order would be maintained.

To enable higher pulse rates to be used, measures to reduce deionising time may be taken, for instance, by the use of special gas atmospheres in the tube. Alternatively it may be arranged to ensure that one or more pulses succeeding that which fires the last gap, are prevented from firing any gaps in the tube so that a time longer than the interpulse interval is allowed for deionisation of the gas in the gaps. Methods of doing this are described in my application Serial No. 777,815, led October 3, 1947, where (inter alia) the reduction of the inter-electrode voltage, so that pulses do not reach the level necessary to cause firing, for the duration of such vone or more pulses, or the use of two or more tubes operating alternately, are outlined.

It is possible to apply a constant inter-electrode potential to the gaps of the tube, insufficient by itself to initiate a discharge in the gaps but sufficient to maintain a discharge, once initiated. With such a potential applied, gaps once fired, Will continue to discharge and at the end of a cycle, all will be discharging and must be extinguished before the next operation cycle of the tube. There are various ways of doing this, one of which is used in the embodiments of the invention to be described.

If no such discharge-maintaining potential is applied, discharges will collapse between pulses, during the firing cycle of the tube and the interval between pulses must not be so long that the ionisation can fall below the level necessary to secure sequential firing.

This involves the use of pulse rates such that the tube has not time to become deionised be- 3 tween consecutive pulses at the end of the ring cycle after eXtinguis-hment of the discharges, and measures such as those described in application, Serial No. 777,815, filed October 3, 1947, become essential.'

In my joint application with C. H. Hough, Serial No. =763f;656, =led-July 25, 1947, aphenornenon occurring in 'multi-gap .tubes :of this type, and called the memory effect, is described.

This effect consists of a rise in the Voltag'e required to fire a gap, which follows an extinguished discharge in that gap, ^wh`e'n"c=ertain electrode materials and gases areused-in A-the construction thereof.

If tubes possessing this feature, are `supplied with pulses to their gaps, incommon, and with no constant discharge-maintaining l'potential,y fa gap once red will ionise the adjacent iinred gap and extinguish at the end of the pulsewhich red it. The next pulse will re the ionised adjacent unredzfgapbut will notreretheex- .tinguished gap v(owing-:to the ysaid rise in its vcritical.nringvoltage), it being arranged that Lthe :pulse amplitude -is belowfsuch critical voltage.

This fmemory effect..-persists longvenough to ensure lthatgap'sronce red, will not againfre ,during theiiring-cycleof the tube, but when all agaps have red and :all possess 'the memory `eifeet,=the rstggap'to-'recover will be that which lhas-been extinguished Afor @the :longest time, vi. `e. `ltheestartingigap, and lthis-'alon'e will fire on fthe first .pulse-of thefnextcycle. A corresponding decay of the memory effect will pass down the -gaps-'oi the tube `in 'the-.predetermined ring,

order,fiin advance of the firing sequence, so that all in turn fare Irea'dy to re from successive pulses.

A @small ibias '-'may be ia'pplied to the starting gap to make quite sure that the sequence S starts lwith that g'a'p linicycles after the-rst, but Athis "biasrru'sthotlbelarge enough-Lto leave'the! startling-'gap permanently discharging. It is also-an advantage "-to-i-'nsert alrela-tively llarge' resistance ladf'infseries `-with oneeofithefcommo'n pulsefe'ed iconnes'tions?to the gaps, -so thateimmediatelyon ttheiirir'i'geofone 'ga'p,l the increasedvoltage drop 'in the resi-stance makes 4lit impossible for fan- -vctherf-g'awp-'to re'i'from the same pulse. This enfables the'tube Vlto"be workedfat fa lower levelof discrimination -fdue '-'to memoryje'ffect between tgaps-andstillsecur'efthecorrectringforder.

l"'If, '-5 in'the 'case of `Va``t1`1bewith `a -maintaining battf'ery and without the lmemory f'eiectftherewis 'abreak -in the pulse traihappliedfto the :tube so that it is 'l'ftiwith ajcertain-numberbf `gaps :'dis'cliarg'in'g, vthis condition will :persist for an 'ihdeiinite timeand `on the-application V0i' pulses "being-resumed the 'tube-will continue 'to -Adis- 'gapfllwing'the'lastzgap'to'b'e i'lred at theti'me `of 1the break. The standing lpotential 4cf the maintaining battery inist be -adjusted so that there is'rio risk fionisationspreading so as to 4 of the tube, such precautions and measures are unnecessary.

It is obvious, of course, that if the last gap is reached by the last pulse before the break, the tube must be allowed to be extinguished so that it recovers its quiescent state ready to commence-a new firing cycle Von'lfth'eresumption of pulsing and the means .provided for extinguishing the tube in its normal cycle, must over-ride iany discharge-maintaining means used for the purposes outlined in the last two paragraphs.

`Fig.`1illustrates a device incorporating a tube of thetypedescribed and the upper half of the ldrawingdepictaa tube of the non-memory type vhaving lten fdischarge gaps.

Thisrdevice is designed to have a number of .gapsred'bys'ighal pulses, after which a system of relays causes a master pulse train to be applic'dtothe tube, ring the remaining gaps of the tube until, on reaching the last gap, the tube `is :extinguishedzand the LYmaster -i-pulse disconnected. :Means are provided for-producing an impulse for every master pulse so applied to fthe vtube,-and the -number of these impulsesvis, of

i lcoursepthe complement of the vnumber of signal pulses-to the "total: number-,of pgaps'- of the-tube.

This y.information may be delivered lup imme- .diately Aor -storedand-delivered later; by breaking the `connection-to the masterpulse source'and only-connecting it v'when `the `information is re- .quired y, The tube I has a-commonanodel'andvcath- -,odes "3 -and A4, cathode d havingA nine L projections like' the teeth of a comb, "towards :the anode, .de- Ylining.'nine-.gaps 15,--:6, '1v-859,440, H,v t2 and t3 between-3 and-2,:and cathode dhavng a-surface lof a larger area than the other rcathode points, dening .a tenth gap -`I4 between ,'-2 -and 4.

AGap A5, the vstarting .-gap, .is f-shorter than the others to ensure that a iirstpulsewill vi'lre that rg'a.p'in-,preference to fthe-others whenzthe tube is .deionised Theagaps'fto :Illfare all of thesame .length-1 andY are vsuchathat af-,pulse -w'ill' only `fire them when the gas within them is Sionised bya idisch'arge *in an :adjoining gap. The anode, .throughafresistance El 6, cathode 13,-- through a rer'sistance H, andcathodefd, throughfa resistance I8, are connected to a battery 20 (representing yearlyconvenient source fofconstant potential) andfthe potential of=this battery vis such that1it :cannot by itself-initiate any discharge, but is suincientfbyfitself, toimaintainfa discharge, once initiated.

`1=2ulses fare 4applied tothe gaps-of `the .tubeA through fa feed: condenser t9.

When,.in1a;sequence'f discharges fin" the tube, ?gap Lisredpia condenserfrz; connected across "anode 2 tand vcathode .4,'and1normally charged to a potential somewhatrzhigher 'than ithatzof lbatteryfiZ avmanner )to'rbe-describedns dis- -.charged .acrossfgap M, eand Flowers the llinter- :electrodeapotential f across fallfgaps` to Va Y value be- 4^low '-.that v'required V'to maintain ra discharge, "whereupon the :discharges are aextinguished. vThis extinguis'hment 'surgezisrassist'edbythe use of a relatively high resistance'for fIS, thelarger 'areafof cathode'-f4i-passingfa*higher 'current in .'gap M ztl'ianfthei other :gaps :andi-causing? a sharp voltage drop facross" t6.

fl`he tarea-"off"47 cannot be indenitel'y extended, .howevergorithe -generalzlevelfofrionisation of the tube b'elT-.incr'easedf-to such-.an f extent'b'y" the iin- 'z'creasedwurrentpassing:ingapI lkthatlthe critical :firing volt'agei'zoffithe --gapsl.-is :lowered to fa point Enabllfgithemt'lee during thesamelpulsefas `alsoaooe that which res I4, keven on the lower voltage pro- 'duccd bythe discharge of condenser 23 and the area of 4 is a limit to the number of gaps which can be extinguished in this way. When this limit is reached, for any design of tube and pulse rate, other methods of extinguishment may be resorted to, such as an external switching circuit or quenching pulse generator, triggered by the discharge current of the last gap, to switch off or oppose the battery 2l). In Fig. 2, contacts b4 and d4 switch o the battery momentarily and similar relay arrangements could be incorporated in the circuit of Fig. l for the same purpose. Connections 24 and 25 are taken from the pulse input points of the tube, to the signal pulse generator 26 which contains a battery 21 and pulsing contacts IP. Signal pulse generator 26 is intended as a symbol of a pulse generator, such as might be used in connection with the device, and might be a key sender or dial in a telephone system, for instance, arranged for make impulsing.

Master pulse generator 28 is connected via transformer 29, in one leg, to 24 and 25 through contacts dI, d2, normally open.

Relay A is connected in series with one connection between 26 and 24 and 25.

When contacts IP are closed, on the first pulse of a train of signal pulses, one pulse is passed to the tube which adds to the potential across the electrodes from source 20, ring the starting gap.

This pulse also adds to the potential across the condenser 23 causing this potential to become larger than that of the source 20.

Relay A operates, operating B over aI front contacts. B operates C, over bl front contacts, and C holds over c2 front contacts, cI back contacts. Contacts cI also prepare an operating path for D, on the release of B. Subsequent operation of IP contacts re successive gaps of the tube I and A impulses in time with IP.

B, being slow to release, holds during the impulsing of IP and A, over al and releases at the termination of the signal pulses after the expiration of its release lag.

Contacts IP are now open and 26 is thus disconnected from the tube.

The release of B operates D over cl front confacts, bI back contacts and dI, d2, front contacts, connect master pulse generator 28, to the tube, the pulses therefrom firing the remaining uniired gaps of the tube and recording an impulse at terminals 36, from transformer 29, for each pulse.

When the last gap is fired, relay E operates kfrom the discharge current through gap I4, being connected in the battery negative connection to the cathode of that gap only.

Relay E, operating, breaks the holding circuit of C at eI. C releases, releasing D at cI, disconnecting 28 from tube I at dI, d2, open. All relays quired to hold the information for later delivery. ,To achieve this, it is only necessary to break the circuit between master pulse generator 28 and` `contacts dI, d2, for instance, with a switch or re-6 lay contacts, normally open.

After the termination of signal pulses, the de-` vice would then remain indenitely with a certain number of tube gaps discharging, with relays A and B released, relays C and D operated and contacts dI, d2, closed ready for the switching-in of 4the master pulse on closing of the said switch or vrelay contacts. There is sometimes difculty in securing a sufficiently stable inter-electrode voltage in the tube owing to the varying currents drawn as different numbers of gaps are discharging from time to time. Accordingly it is advisable to insert choke 2l and rectifier 22 connected between the anode and a tapping on the battery 20.

, The tapping is chosen so that the rectier 22 is just non-conducting when all gaps are iiring, that is to say, when the voltage drop across resistance I6 is at its maximum.

The precautions previously mentioned, to ensure that ionisation does not spread to more than one gap adjoining the last fired gap, should be borne in mind and, where there is no maintaining battery, or in the case of a tube with the memory effect, measures must be adapted to prolong the discharges or discharge during the interval between the end of the signal pulses and the application of the master pulse.

This device represents the simplest application of the invention. The functions of the relays could readily be carried out by electronic devices, for instance, the function of relays A and B could be entrusted to a time constant circuit upon'the recovery of which, at the end of the signal pulses, an electronic-flip-flop circuit could be utilised to connect in the master pulses to the tube, the Hip-flop being restored to its original state by a pulse generated by the discharge of the last gap of the tube.

The flip-flop circuit could be of known type and Fig. 2 shows such a circuit consisting of tubes 36, 31 and 38 and their connecting circuits.

It is frequently required that a recording device shall deliver information characteristic of the applied signal pulses in continuous form, and Fig. 2 illustrates such a device where the delivered information continuously denes a time position or phase relationship in or to a continuing sequence of master pulses.

In Fig. 2 a cold cathode discharge tube I is shown, which closely resembles tube I of Fig. 1 and the circuits immediately connected with the operation of the tube are also similar, the same numerical references being used in the two figures for corresponding items. The differences in the two tube circuits are confined to the pulse feed circuit to the tube and the components in the circuit exclusive to cathode 4.

In Figure 2, the circuit of cathode 4 includes a resistance 3l and a transformer 32. The forvmer is connected to a source of audio frequency signal, and voltages developed across 3l affect the precise time of firing of gap I4, so that output pulses from transformer 32, passing through a rectifier 33 which passes only the leading edges of the pulses, and battery 34 which biases rectifier 33 suitably, are recovered from terminals 35, modulated in time by the audio frequency signals.

The operation of the device, in broad terms, is as follows:

Pulses are applied to the tube to fire a number of its gaps.

At the end of these impulses, a master pulse is applied to the tube, not immediately, but 'at acomode a certain Iphase suchimaster `pulses; whichemay be regarded as divided into successive cycles each having anumber `of pulsesequal to the number off pulses in the operating cycle of .the tube. A pulse at a certain phase in such cycle of pulses islregardedfas the Zero pulse of .thewcyc'les and Ymaybe marked. or accentuated in some way or, alternatively, a rseparate zero .pulse .generator maybeused, producing a pulse only at zero phase of the master Vpulse cycles. 'The first-zero pulsewater the vtermination of the-signal impulses, isapplied to .the tube'which tires atanother of its vgaps from the `Zero'pulse 'andcontinues to fire other gaps from the master pulses, giving an output pulse from terminal 35 `on thering of gap ill, after which thedischarges .in thetube are. extinguished. The Vnext master pulse .-after,.extinguishment starts a new ring cycle of the gaps of the tube :which 'continues to -re in repe'atedcycles, indefinitely, till the master rpulse.Y is disconnected.

vThe firing of gap t takes place krepeatedly at Aa definite phase position in the master pulse 'cycleslin relation to `the zero. pulse, and this phase position depends upon the number of signal imn pulses'originally applied to the tube.

The. detailed operation of the circuits illustrated is as follows:

A source B. of impulses and audio frequency .signals is. shownrin .the form ci the microphone .and .dial circuits of a conventional telephone subset, Athough the invention is by no means con- ;ned to telephone systems. Y

The components shown are dial impulse co tacts IP, oir-normal springs ON, switch-hook Gn lifting the receiver, SH closes the loop at the subset end, operating A, through earth, bat.- rtery, top winding of A, Wire t2, IP, SH, .bottom winding of A, earth. operating, operates B Aon al iront contacts. i

Onrcommencement ordi-ailing, ONfront springs yshort-.circuitmicrophone.15e and l'on `the return fof ithezdial, 'each :dial impulse .takes the form of opening IP, A releasing .for each impulse.

1B, being slow to release, holds during the yirnpulsing of al contacts. Meanwhile, Val); contacts apply'positiveimpulses from battery .63 through -pulse input condenser i9, to tube l, via d back 1(or.cll front contacts), b5 front contacts, a2 back ficontacts, the latter contacts `closing every time se. releaseson the opening vorlP.

v0n every impulse of IP one gap .of tube l 'is fired. Y

Thetoperationof the other relays is as follows:

"B, operating, Voperates C, on the first .release of Aafter moving the dial, over d2 back, .h2 :front contacts, ai back. contacts.

`(Z2-being slow to: release, holds `Vover c2, b2, al (impulsing) ,C, operating, operates D, over .c|,. land d2 is opened, leaving c2 to complete the holding cire icuitfiorjCiand ci to complete the pulse circuit for tubek :I, nflieuof. d6.

S D :holds: over dis, bl, both front contacts.

`Atfthe end. of dialling, B holds over al front contacts, since A remains operated over the loop throughfIP, closed, 59, and SH, closed.

C, releases, however, after its release lag, being open-circuited at al front contacts.

Dn C ireleasing, the pulse feed circuitof tube l, from 63, is broken at a2 open Aand c4 open, `cit-.being also open since D remains operated.

` The operation of the flip-flop circuit on the right .in Fig. 2, will now be described.

.A .pentode .36 isA normally biassed positive on its suppressor grid by potential divider di, 42, aconnecticn from its anode being taken through food condenser 3Q tothe pulse input of tube i.

Valve 3&3 is ,also normally cut oi on its control grid which is connectedtothe grid of one Valve .Si of .the nip-flop circuit having two valves 31 and 3E.

The anodes of @l and 38 are supplied with high tension current through anode loads d5 and d6 respectivelyhe anode of valve :il being connectedto. the grid o valve Sii through resistance 69 and the anode of Valve 38 being connected to the grids of valves 36 and 3l through resistance 4l. Valves and are given a standing grid bias by battery 5l, through resistances i8 and 5t respectively.

This is a conventional flip-flop circuit with two stable conditions, one with one valve conducting and the other cut oi, and the other, viceversa. c

Normally, Se is conducting and its anode applies negative potential to the grid of 31 holding .it andalso in the non-conducting state.

When, at the beginning of dialling, C and D are both operated, c3 is open, and d5 closed, c3 opening before dii closes, since C operates before D.

When B releases at the end of dialling, C releases, closing e3 and completing a path through Vc3 and d5, to the grid of 33, from zero pulse generator 5e. Zero Apulse generator 55 emits negative pulses at .zero phase of master pulse generator iil, and the rst zero. pulse after the release of C, at the end of dialling, cuts ofi i3 from the anode of which the control grids of and 31 receive a positive bias due to the rise in anode voltage on cessation of anode current through 46, and 3i becomes conducting, whilst the control grid of 3e is opened Master puise generator is permanently connested to the suppressor grid of 36, through feed A condenser 52,. and when the Zero pulse causes the #flip-flop izo-change over and Se control grid becomes open, the anode potential of falls negative (which doesl not affect tube l) and the ,next master pulse after the Zero pulse, cuts off the suppressor grid of causing a positive pulse to appear on tube i via condensers Sii and i9. Successive master pulses continue to cause positive .pulses to be applied to tube i, firing its gaps in succession in repeated cycles, as previously de- Vvscribed.

-at the same time as the Zero pulse, cuttingoi 36 fon its suppressor .grid `when the control grid of 235 is opened, butthe negative pulse mustcome sooner or later, whenboth pulsesare absent.

It can'be arranged, however, that the `extinguishment of tube I will not aect its operation,

response to the continuing master pulses, a pulse Y is passed to terminals 35 at the required phase position in relation to Zero phase of the master pulse cycles and the precise firing time or gap I4 and of the pulse from 35 will be varied according to the instantaneous potential across 3I which is varied by the audio frequency signals from microphone 59.

There has thus been secured a succession of time modulated pulses at a phase in the master pulse cycles determined by the number of impulses dialled from subset 64, and this pulse may be applied to a distributor in those telecommunication systems where individual substations are allotted to, or communication channels are represented by, time positions in a cycle of pulses.

When the call terminates, ISH contacts are opened, A releases, releasing B at al back contacts, D releasing in turn at bl open. B, releasing before D, closes a circuit at d3 front contacts, b3 back contacts, connecting a battery 53 to the grid ci 31 through condenser 54, applying a momentary negative pulse to 31, cutting oiT 31 and 3'6 on its control grid, and restoring the filipflop to its other stable state. This circuit is later cut, on the release -of D, after its release lag. The zero pulse generator path to 38 grid is now br-oken at d5.

The tube I is protected from false impulses.

y the release of B and the release of D, that is to say during the release lag of D, the negative battery load to tube I is momentarily disconnected at d4 so that the tube is extinguished. This is f necessary because at the termination of a call the tube will usually be left discharging on some of its gaps, there being no further pulses to extend the ring cycle to the end of the array of gaps and cause the normal extinguishment measures to operate.

The circuit is now as drawn cept new dial signals. 1

The functions performed by the. relays could equally well be performed by corresponding electronic devices, for instance several flip-ncp circuits of the type described could readily be made to do the same tasks. Where operating speeds are within the capacity of relays, howevenit wil-l frequently be advantageous to use relays to avoid added 'tubes and their power supplies.

Th device shown in Figbz is capable of'accepting a single train of pulses only and, with the simple subset shown, would only deal with single digit impulse trains. Y

This particular arrangement is only intendedas an example to illustrate Vthe nature of this einbodiment of the invention. For use in larger systems, it is envisaged that signal impulse trains of considerably more than ten, will be used, in

and is ready to ac- 1Q combination with gas tubes having a correspondingly large number of gaps.

Alternatively, successive stages of selection may be introduced into a system responsive to successive digits in a decimal numbering system, though here, the simple system of impulsing described would need modification to the extent of passing digits after the first to the modulating part of the circuit and outward from terminals 35 whence, after dem-cdulation, they could be used to provide signal impulses for a similar device responsible for secondary selection.

If a device of the type shown in Fig. 2 is used in a telecommunication system, though it is of course by no means coniined to such application, it can be connected directly to the termination of an incoming distribution line and one such device will be required for every such incoming line.

There are systems where a limited number of interconnecting links are available to a larger number of incoming lines and when a device of the line finder type is used to connect a free interconnecting link to a calling line, a system of this type where individual lines are allotted to individual time positions in a repeated cycle of pulses, is described in the application of David Ransom et al., Serial No. 794,724, filed December 30,1947.

` In a system of this type a line nding device searches for and locks to the time position of a calling line and pulses at that time position, modulated by designation or other signals from the calling line, are demodulated before being passed to selecting apparatus responsive to designation signals, adapted to select a time position allotted to another line incoming to the system to which connection is required.

The device illustrated in Fig. 2 could readily perform this selection process by the application' of demodulated signalling impulses to lines 62 and 63 in place of subset 64, the master pulse gen-l erator and Zero pulse generator being synchro-J nised with the distributor or other means entrusted with the transfer of the incoming lines to the various time positions to which they are allotted in the cycle of pulses.

According to the number of such signal impulses, therefore, so will the timing of the pulses emerging from terminals 35 coincide with the time position allotted to one or other of the other lines incoming to the system. These timed pulses may be applied to the same distributor as that which originally distributed the incoming lines into the time cycle or to a separate outgoing distributor, as is used in the said application last referred.

The embodiments shown in Figs. 1 and 2 make use of a tube without the memory effect and in which extinguishment of discharges at the end of a ring cycle is entrusted to condenser 23. Other methods of extinguishment may be used,

however, such as a direct disconnection of the standing potential by relay or similar means, triggered by the discharge in the last gap or by a local quenching pulse similarly triggered. This would do away with the need for condenser 23.

A tube having the memory eiiect could be used in either application, in which case, in the Figure 1 arrangement, the stabilising circuit 2 I, 22 would be unnecessary, whereas in the Fig. 2 arrangement, the need for speciiic extinguishing means, at the end of a cycle, would also be unnecessary.

It has already been pointed out, however, that, if there is a break between the end of the signal amend l. l pulses and the application of thiexmaster pulses which exceeds the deionising time ci the tube, measures mustbetaken to prolong the discharge in the'gap red by the last signal vpulse so that the master pulse fires the next gap thereafter and does not start from the beginning of the tube.

In the circuit of Fig. 2, it would Aalso be possible to resort to the arrangement describedin myapplication, Serial Number 777,815, filed October '3, 1947, whereby, at thev end of a firing cycle, one ormore pulses are prevented from causing discharges in the tube to allow extra timefor deionising where-pulse rates are used which do not allow :time enough for deionising between consecutive pulses'.

In describing the embodiments shown in Figs. land 2, the possibility of applying an initial train of .signal pulses greater in number than the firing cycle of the tube, has not been mentioned, but it will be obvious that this might beV done and fit-s within the'scope of the invention. Y

In such a case,'the tube'wouldpomplete ahum,- ber of operative cycles equal to the number :of complete multiples of .the pulsesinthe cycle, contained inthe numb'er'of appliedsig'nal pulses and thereafter would re a number Vof gaps equal to the balanceof'the signal pulses.

rlhis might, for instance, be used to record the units digit of a multi-digit number, the other digits, derived either from a circuit connected'to the last gap 'of the tube, or in some other Way, being recorded elsewhere.

What is claimedis:

,1. An electronic device Vwhich comprises a-cold cathode gaseous discharge tube having a number of gaps arranged in'sequence toire in succession in a predeterminedV order on the application, `to the said gaps, of consecutive pulses of electrical energydue to the influence of a red gap on the potential required to fire an adjacent unredgap, means for applying in turn to 'the said ytube av firstgroup of pulses, means under control of-said lrst means and responsive tothe end of thelast pulse of said first group for applying to :the :said tube a second group Voi pulses, and means also under control of said li-lrst means forgiving a signal dependent on the firing 4.of :a predetermined gap during the application of theY second group of pulses.

2. An electronic device, as claimed insclaim 1, in which the tube is arranged to respond .to repeated cycles of pulses, each having `pulses `at least equal in number to the number of the said gaps, and in which the second group of pulses contain a number of such cycles, the said signal being repeated each time the said predetermined gap is iired and deiining a phase position in each cycle.

3. An electronic device, as claimed in claim 2, comprising means for producing a repetitive connecting signal synchronized with .the first :pulse in .each cycle of said-second group, the means for applying the secondgroup of pulses also lie- 12 comprising means for modulating the signal dependent on the firing ofthe predetermined gap.

5. A device, as claimed infclaim 1, in which the tube is arranged to respond to repeated cycles of pulses, each having pulses at least equalin number to the number of the gaps, and in which the second group of pulses contains a number of such cycles, the said cycles being repeated each time the said predetermined gap is iired and defining a phasejposition in each cycle, and further comprsing'means for producing a repetitive connecting signal synchronized with the first pulse in each cycle of said group, and means for applying the second group of pulses comprising an electronic circuit having two stable conditions in the first of which pulses of the second group are withheld from the said gaps and in the second of which pulses of the said second group are applied to the said gaps, and means for causing said connecting vsignal to shift said circuit from said rst condition to said second condition.

-6. Anele'ctrcnic device comprising a cold cathode gaseous discharge tube having a gap adapted to Vdisclmrge during the application thereto oiv pulses of electrical energy, means Yfor applying pulses to said gap, means connected to said gap for producing a signalwhen said gap iires, andmeans for modulating the pulses applied to said gap so as to vary the time of firing and thus modulate the signal with respect to time.

7. An electronic device, as `claimed in claim 6, in which means is provided for extinguishing the said gap between successive pulses of a sequence of pulses applied theretoand in which the sig- Hals, dependent on` the repeated iiring of the said gap during-the application Aof thesaid pulses, are successively modulated by the said modulating means.

8. An electronic device, as claimed in claim 7, in which .the modulating means includes means responsive to audio frequency current or voltage.

9. An electronic device, as claimed in claim 6, in which the said gap is one of several gaps ln a cold .cathode gaseous discharge tube such gaps being adapted to fire in succession in a predetermined order on the application of consecutive pulses of electrical energy due to the'inluence of a fired gap on the potential required to lire an adjacent unred gap, and in which means is pro vided for extinguishing the said gap between successive pulses of a sequence of pulses applied thereto and in which the signals, dependent on the repeated firing of the said gap on or during the lapplication of the said pulses, are successively modulatedby said modulating means.

ALEC HARLEY REEVES.

REFERENCES CITED Y The following references are of record in the le of this'pat'ent:

UNITED STATES PATENTS Number Name Date y2,404,920 Overbeek July 30, 1946 2,443,407 Wales June 15, 194,8

Certificate of Correction Patent No. 2,505,006 April 25, 1950 ALEC HARLEY REEVES It is hereby oertied that errors appear n the printed specification of the above numbered patent requiring correotlon es follows:

Column 1, line 36, strike out the Words and comme 110W ebandoned,, and msert the same in line 38, same column, after July 25, 1947,;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case 'm the Patent Office.

Signed and sealed this 22nd day of August, A. D. 1950.

[SEAL] THOMAS F. MURPHY,

Assistant Gommzsszoner of Patents. 

